Zinc base alloys



Patented May 28, 1946 Edward SQBunm Rome, Yiaa ssignor to Revere Copper and Brass Incorporated, Borne, N.Y.,.

a corporation of Maryland No Drawing. Application une 10, 1 943,"

Serial No. 490328 2 Claims. (o1. 755178;

My invention, which will be best understood from the following description, relates to zinc base alloys.

The invention has among its objects the production of zinc base alloys of improved characteristics, particularly in respect to excellent mechanical working properties combined with high tensile strength, ductility and resistance to impact loading or shock, and a satisfactory degree of stability for most uses of the alloys in all these latter respects as they age.

The improved alloys contain approximately 0.6 to 5% copper, 0.05 to 0.25% silver, 0.1 to 0.75% antimony, balance zinc. To secure the desired properties of the alloys the amount of silver present should not be greater than approximately the amount of antimony present, best results being secured when the amount of silver is not more than about 50% of the amount of antimony. Further, to secure these desired properties the sum of the amounts of antimony and silver should not be more than about 25% of the amount of copper.

The improved alloys are characterized by the capability of being readily worked hot or cold by commercial processes, and when so worked have a degree of ductility and other mechanical properties much superior to those of ternary zinc-copper-antimony alloys similarly worked, and furthermore are markedly more resistant to shock or impact loading. Still further, the improved alloys are dimensionally stable as they age, and are not subject to intergranular corrosion. In fact, so far as can be determined, the improved alloys exhibit no dimensional change or intergranular corrosion at all when aged.

Outside the ranges and proportions of constituents above specified the quaternary zinccopper-antimony-silver alloys do not possess the combination of properties above enumerated. For example, the alloys are not satisfactorily hot and cold workable in a commercial sense if the sum of the amounts of antimony and silver exceeds approximately one-quarter the amount of copper, and, if the amount of silver exceeds the amount of antimony, the alloys are in general deficient in resistance to shock and generally lack satisfactory stability in respect to maintaining a satisfactory degree of ductility as they age. v

The excellent properties imparted to zinc by adding thereto copper, antimony and silver in accordance with the present invention, are indicated by the following table of properties of thehot rolleds metal, inrwhich table thesteam test referred .to is :the standard. accepted test, for determining thestability of zinc and zinc base alloys with age, consisting in subjecting the metal to moist steam at 95 C. for 10 days:

Before steam test Oharpy impact Per- Per- Per- Tensile Percent elonstrength (ancent cent cent strength, gation in nealed at 600 Cu Sb Ag p. s. i. 2 inches F. for 1 hr.)

ft./p. s. i.

2. 3 0. l O l 38, 000 50 500 After steam test Cltarpyg tililngiact Per- Pcr- Per- Tensile Percent elon- S fen cent cent cent strength, gation in g g f g; Cu Sb Ag p. s. 1. 2 inches 0118 steam lest) ftJp. s. i.

5 O. l 0. l 40, 000 35 310 5 0. 75 0. l 40, 000 30 300 As pointed out in applicants copending application Serial Number 479,112, filed March 13, 1943, workable alloys can be secured by adding small amounts of copper and antimony to zinc, that is to say, without adding silver. However, in such ternary alloys the amount of antimony is rather critical, varying inversely with the amount of copper, so that when the higher amounts of copper are employed the amount of antimony must be small and the range thereof very limited to secure a workable alloy of high tensile strength. Further, with such ternary alloys the ductility rapidly decreases as the amount of copper is increased, making the alloys with the higher amounts of copper, as compared to many other zinc base alloys, commercially suitable only for forging and die casting purposes.

Addin copper and silver to zinc, it has been found, secures a ternary alloy which, as compared to the improved quaternary alloy according to the invention, has a lower tensile strength making it unsuitable for many uses. Further, such ternary alloys are much more unstable as compared to this quaternary alloy in respect to maintaining it valuable properties with age.

It has been found that adding both antimony and silver together with copper within the ranges and proportions above specified secures about the same tensile strength as if the silver were omitted. However, when silver is added the alloys with the higher amounts of copper have much higher ductility and hot and cold plasticity, and can be worked by rolling by commercial processes as Well as forging. This increase in the ductility of the improved alloys having the higher amounts of copper is very marked, with the result that alloys of high tensile strength capable of being rolled hot and cold can be secured by increas- 7 percentage amount of antimony present and the ing the amounts of copper without an unsatisfactory decrease in the ductility for many uses of the alloys. Further, adding both antimony and silver with the copper results in the alloys being much less critical, as compared to the ternary zinc-copper-antimony alloys, in respect to the amount of copper that can be employed for the amount of antimony present, thus enabling alloys with the desired properties to be secured with more assurance in commercial practice.

sum of the percentage amounts of silver and antimony present being not substantially greater than of the percentage amount of copper present, the balance being substantially zinc.

2. The alloysaccording to claim 1 in which the percentage amount of silver present is not substantially greater than of the percentage amount of antimony present.

EDWARD S. BUNN. 

